SUMMARY The graying global population makes interventions to extend healthy lifespan a public heath priority. Health insults during the perinatal period are linked with risk for aging-related health conditions, including obesity, type 2 diabetes, and cardio-metabolic disease. If these associations are causal, interventions to prevent perinatal insults and to reverse their biological damage could delay disease onset and prolong healthspan. However, establishing causal long-term health effects of perinatal insults in humans is challenging. Randomized trials would be unethical. Observational studies can be biased by confounding factors that erroneously suggest a link between insults in the perinatal period and later health. In contrast, natural experiments can isolate the impact of perinatal insults on adult disease and healthspan. The Dutch Hunger Winter Families Study (DHWFS) uses a sudden, war-induced famine as a natural experiment. The famine was caused by a Nazi blockade during WWII in 1944-45. Because the impact of famine was immediate, transient, and population- wide, DHWFS comparison of infants born during the famine with those born before or after the famine will identify potential long-term effects of perinatal-insults. However, famine natural-experiment studies, including DHWFS, may be vulnerable to selection bias. Birth rates decline significantly during famine; famine?s impact on fertility and fetal/infant survival might bias famine studies of perinatal insult?s long-term effects in unknown ways. To fill this gap in knowledge, we will genotype stored DHWFS biospecimens from of N=956 individuals, 37% of whom were exposed to famine in-utero and the remainder of whom are siblings of the famine-exposed individuals and ?time controls? born immediately before or after the famine. We will link new genetic data with participants? existing clinical and cognitive tests and blood DNA methylation data. We will examine in this integrative multi-omics database the potential impact of selective fertility and fetal/infant survival during the famine on (i) genome wide genetic characteristics; (ii) differences in polygenic risk scores for specific aging- related health conditions; and (iii) differences in methylation quantitative trait loci (mQTL) genotypes. We will then conduct genetics-informed analysis of famine effects on obesity, type-2 diabetes, cognitive reserve, and epigenetic aging. Using these new resources, we will prepare an integrated multi-omics database of the DHWFS population for use by outside research teams and generate a one of a kind resource for famine and perinatal insult research. The proposed project will generate a new knowledge base to further examine biological pathways that are likely to connect perinatal events to adult health and aging through genetic and epigenetic mechanisms.